Justification:
This species has experienced rapid declines across most of its European range. Population trends outside Europe are unknown. Extrapolated over three generation lengths and allowing for uncertainty, the population is thought to be declining at a rate sufficient to trigger Vulnerable under the population size criterion. Should population trends become less uncertain both within and outside its European range it may merit uplisting or downlisting.

The Atlantic Puffin can be found throughout the North Atlantic Ocean, from north-west Greenland (to Denmark) to the coastline of Newfoundland (Canada) and Maine (USA) in the west, and from north-west Russia down to the Canary Islands, Spain (in winter) in the east (del Hoyo et al. 1996). The population in Iceland and Norway, which together account for 80% of the European population, decreased markedly since the early 2000s (BirdLife International 2015). In much of Iceland breeding has generally failed every year since 2003, but in the north, at least, it has been borderline sustainable (G. A. Gudmundsson in litt. 2015, E. Hansen in litt. 2016, A. Petersen in litt. 2016). The largest Norwegian colony, Røst, has experienced sharp declines from almost 1.5 million breeding pairs in 1979 to only 289,000 pairs in 2015, and has produced virtually no chicks in the last 9 years (T. Anker-Nilssen in litt. 2015, Anker-Nilssen et al. 2016). Most other Norwegian colonies are much smaller, including that at Runde, which has also declined; however most colonies remain unmonitored (A. O. Folkestad in litt. 2015, T. Anker-Nilssen in litt. 2015, 2016). Numbers on the southern coast of the Barents Sea have increased such that declines in the total population in Norway are estimated at approximately 33% since the early 1980s (Fauchald et al. 2015). Populations in the Faroe Islands (Denmark) and Greenland are also reported to be decreasing (BirdLife International 2015).The population size was estimated to be increasing in the U.K. during 1969-2000, and populations in the North Sea are probably currently stable or increasing after a decline in the 2000s due to two very low overwinter survivals of adults (Harris and Wanless 2011, Harris et al. 2013). A reduction in the recruitment of juveniles into the breeding population is thought to be the most likely factor involved in a sharp decrease in the number of puffins at the Fair Isle (U.K.) breeding colony; from approximately 20,200 individuals in 1986 to 10,700 individuals in 2012 (Miles et al. 2015). Adult survival probability remained similar across the 27 years of the study, whilst breeding success, the number of feeding visits by adults to chicks and the size of available prey fish all decreased. Trends from North America are uncertain, with the population at Great Island, Witless Bay showing increases between 1979 and 1994, but it has potentially stabilised or is in decline now (Wilhelm et al. 2015). A restoration project off the coast of Maine has also had some success (D. Wege in litt. 2002, see http://projectpuffin.audubon.org/).

The European population is estimated to be 4,770,000-5,780,000 pairs, which equates to 9,550,000-11,600,000 mature individuals (BirdLife International 2015).

Trend Justification: The population size in Europe is estimated and projected to decrease by 50-79% during 2000-2065 (three generations) (BirdLife International 2015). Europe holds >90% of the global population, so the projected declines in Europe are globally significant. The overall trend of the West Atlantic population is unknown (Berglund and Hentati-Sundberg 2014). Populations are suspected to be declining rapidly through the combined impact of predation by invasive species, pollution, food shortages caused by the depletion of fisheries and adult mortality in fishing nets.

The species is exclusively marine, found on rocky coasts and offshore islands (Nettleship et al. 2014). It nests on grassy maritime slopes, sea cliffs and rocky slopes. During the winter it is wide-ranging, found in offshore and pelagic habitats.

The species is a pursuit-diver, catching most of its prey within 30 m of the water surface but capable of diving to 60 m (Piatt and Nettleship 1985, Burger and Simpson 1986). They prey on 'forage' species, including juvenile pelagic fishes, such as herring Clupea harengus, juvenile and adult capelin Mallotusvillosus, and sandeel Ammodytes spp. (Barrett et al. 1987). At times, they also prey on juvenile demersal fishes, such as gadids; planktonic crustaceans; and polychaete worms (Harris and Hislop 1978, Barrett et al. 1987, Martin 1989, Rodway and Montevecchi 1996, Harris et al. 2015). In the southern and eastern parts of its range, sandeels usually form the majority of the prey fed to chicks (Corkhill 1973, Hislop and Harris 1985, Harris and Wanless 1986, Martin 1989, Harris and Riddiford 1989). However, there are exceptions, such as at Skomer Island in 1969 when sprat made up the majority of the diet fed to chicks (Corkhill 1973), and in the Lofoten islands, where first-year herring are often the commonest food of chicks (Anker-Nilssen and Aarvak 2006).

When feeding chicks, birds generally forage within 10 km of their colony, but may range as far as 50 to 100 km or more (Harris 1984, Anker-Nilssen and Lorentsen 1990, Rodway and Montevecchi 1996). A boat transect run on one day in 1970 found that 85% of all birds seen were concentrated within just 3 km of the colony (BirdLife International 2000), but other studies have found peaks in the density of foraging birds at up to 40 km distance from the colony (Webb et al. 1985, Stone et al. 1992, Stone et al. 1993, BirdLife International 2000). Similarly, surveys and GPS tracking at the Isle of May, Scotland, suggest that birds forage close to the breeding colony, but also at other sites up to 40 km away (Wanless et al. 1990, BirdLife International 2000, Harris et al. 2012). Various studies (Pearson 1968, Corkhill 1973, Bradstreet and Brown 1985, BirdLife International 2000), based on different breeding colonies, have estimated the theoretical maximum foraging radius at anywhere from 32 km (Corkhill 1973) to 200 km (Bradstreet and Brown 1985).

This species is highly susceptible to the impacts of climate change, such as sea temperature rise and shifts in prey distribution and abundance (Durant et al. 2003, Sandvik et al. 2005). This is a particularly important threat when prey species are exploited unsustainably, leading to prey reductions and subsequent unsuccessful breeding. Breeding failures are usually assumed to be due to food shortages (e.g. Martin 1989, Anker-Nilssen and Aarvak 2006, Harris and Wanless 2011, Anker-Nilssen et al. 2016). It is vulnerable to oil spills and other marine pollution. Extreme weather events and storms also pose a threat, with large wrecks recorded following severe winter storms at sea. At the breeding colonies the species is vulnerable to invasive predators, such as rats, cats, and American Mink Neovison vison. The species is susceptible to being caught in gillnets, although other fishing gears may also catch significant numbers. Increasing numbers of offshore wind farms may result in displacement from habitat, although the risk of collision is considered very low (Bradbury et al. 2014). The species is hunted for human consumption in Iceland, and in the Faroe Islands (Thorup et al. 2014). Harvesting, livestock grazing and tourism at its breeding grounds pose additional threats due to disturbance (Nettleship et al. 2014).

Conservation and Research Actions UnderwayThe species is listed under the African Eurasian Waterbird Agreement. It is included in the Action Plan for Seabirds in Western-Nordic Areas (TemaNord 2010). There are 76 marine Important Bird Areas identified across the European region. Within the EU there are 40 Special Protection Areas which list this species as occurring within its boundaries.

Conservation and Research Actions ProposedFurther identification of important sites for this species, particularly in offshore regions and designation as marine protected areas. Increase knowledge of the species's ecological requirements in winter (Harris et al. 2015). Develop a monitoring schemes to understand population trends (Nettleship et al. 2014). Identify the risks of different activities on seabirds, and locations sensitive to seabirds. Continue eradication of invasive predators from breeding colonies. Management of fisheries to ensure long-term sustainability of key stocks (e.g. sandeels). Establish observer schemes for bycatch and prepare National/Regional plans of action on seabird bycatch. Continue Arctic Monitoring and Assessment Programme (AMAP) monitoring of seabird contaminants; include new contaminants and secure communication between seabird and contaminants research. Develop a system to monitor and predict impacts of offshore oil developments on important areas for the species, in particular, key wintering sites (Nettleship et al. 2014). Increase the level of understanding among the public of introducing hunting restrictions. Develop codes-of-conduct for more organised activities (e.g. tourism). Ensure that appropriate protection (national laws and international agreements) applies to new areas and times in cases of changes in seabird migration routes and times.